Niobium to alcohol mol ratio control of the concurring esterification and etherification reactions promoted by NbCl5 and Al2O3 catalysts under microwave irradiation

Alcohols and acids can be switched to produce ethers or esters by varying the alcohol to catalyst mol ratio, in a new etherification and esterification method using NbCl5/Al2O3 catalyst under “solvent free” conditions and promoted by MW (microwave) irradiation. A “two sites” mechanism for the reaction is proposed, in an attempt to clarify the tendency of the catalyst to be dependent on the alcohol alone during the esterification process.

Graphical abstractAlcohols and acids can be switched to produce ethers or esters by varying the alcohol to catalyst mol ratio, in a new etherification and esterification method using NbCl5/Al2O3 catalyst under “solvent free” conditions and promoted by MW irradiation. A “two sites” mechanism for the reaction is proposed, in an attempt to clarify the tendency of the catalyst to be dependent on the alcohol alone during the esterification process. Dependency of product distribution to the NbCl5 to alcohol mole ratio for the esterification of benzyl alcohol with glacial acetic acid. Reaction conditions: 5 min MW irradiation at 360 W; acetic acid, 2.8000 mmol; benzyl alcohol, 1.0000 mmol; 0.1000 g of Al2O3. Determined by 1H NMR.Figure optionsDownload full-size imageDownload as PowerPoint slide